Converting DVD Audio to CD Audio (Mac OS X)
May 17, 2004
Updated: December 2004
We bought a DVD Audio album mistakenly,
instead of the CD Audio version. The problem
was that we don't use the DVD player for
anything other than watching rented movies and videos for the children.
Although the DVD Audio
content is recorded in 5.1/surround, we are not likely to start buying
DVD Audio content in the near future.
I looked for a a freeware ripping/encoding program but the ones that I
found for Windows would convert an entire disc if the full purchase
price (about $30) was paid
first. They look like they would be fine programs: the user interfaces
are easy-to-use and they separated tracks individually. Furthermore,
they can convert copy protected (CSS-encrypted) audio material. I
didn't find an integrated program for the Mac.
So instead of buying a program to do that, I used free programs, or at
least programs that I had, converting a DVD Audio disc into CD Audio.
The
DVD Audio album contained the same tracks and track lengths as
the CD Audio album available for sale, so making iTunes recognize the
CD was also important.
Steps for Converting DVD Audio into CD Audio
The following steps give an outline of how to convert a DVD Audio file
to CD Audio using free programs available around May 2004.
My setup is:
- G4 Dual 1GHz (QuickSilver), 1GB RAM, SuperDrive DVR-104
- Mac OS 10.3.3 (Panther)
- QuickTime Pro 6.5.1
- iTunes 4.5
- DVD
Backup 1.3 (December 2002)
- bbDEMUX 1.0b (February
2003)
- mAC3DEC
(March 2004)
- Roxio Toast 5.2.3 (Toast is not necessary but I recommend it)
Convert DVD Audio to .VOB
On the Mac I have used DVD Backup
to rip the DVD files (removing CSS
and region encoding) which I can later burn to a new DVD-R using Toast.
This step
usually produces .VOB, .IFO, and .BUP files. This step seems reasonably
fast,
I think
faster than 1x DVD on a G4 1GHz machine with a SuperDrive.
Demux .VOB to .AC3
Next I used bbDEMUX
to split the multiplexed .VOB files into its audio
and video component streams, which might include .m2v or .ac3.
Then I used mAC3DEC
to convert the .ac3 file into AIFF (uncompressed
Mac audio, or what you would get if you ripped a CD audio disc). This
step takes something like a "48 kHz 5.1 AC-3" audio stream and
converts it into "44.1 kHz Stereo AIFF". DVDs use a 48 kHz audio
sample, with six channels, and CDs use 44.1 kHz audio sampling in two
(stereo) channels.
Convert .AC3 to .AIFF
At this point you have a single .AIFF (or .MP3) file. In
my case, the album was converted into a single file and not multiple
tracks the way you would usually find it on a CD. Also, there were two
.AIFF files, splitting the entire album into two contiguous audio
streams. I concatenated the two .AIFF files into one and then saved a
new .AIFF file that contained a single track of the entire album.
Split a Single Album AIFF into Track AIFFs
Next, I split the album into tracks that were the same length as the
original CD album. Using the FreeDB.org web-based
search page, I found the album and the track lengths. Next, I
selected AIFF tracks using QuickTime Pro and
then exported it back to AIFF as one file. For each track I copied
exactly the number of seconds that were listed on the FreeDB page,
pasted it into a new QuickTime Pro window and exported each window's
contents individually as AIFF.
Assemble AIFFs for Burning to CD
Now with a collection of individual tracks in hand, I imported
(dragged) the
files into iTunes. iTunes and programs that use the CDDB/FreeDB CD
databases recognize CDs by track lengths, so there are
a few ways to make a CD look very close to the original:
- Burn AIFF to CD directly with no pause between tracks. If you
leave a slight pause (e.g. 2 seconds), then the disc will be burned
with tracks that are two seconds longer, not with two seconds between
tracks. The drawback is that the inter-track pause might not be long
enough.
- Convert AIFF to MP3 and then burn the MP3 tracks. This seems to
preserve the track lengths, but then you might have short gaps on your
CD. Also, it has the obvious drawback that you are converting between a
lossless format (AIFF) to lossy (MP3) and then back to the lossless (CD
audio) format.
- Use Toast to create an audio CD. Drag the AIFF tracks and
manually set the inter-track pause time. I chose to use this method.
Because I wanted to see whether iTunes would pick up the track titles
from the CD track times, I first attempted some trial burns using
CD-RW. After a successful burn, I imported the tracks into iTunes,
ripping the CD and encoding it into MP3.
Random Comments
I'm not completely familiar with the DVD Audio format. The DVD Audio
disc that we bought simply appears to be a DVD Video disc with still
images and an audio track. No doubt you could find out a lot more elsewhere.
The audio quality of the CD seems to be "good enough." I'm not going to
claim
this is audiophile quality or that this is the best way to convert
between formats.
The audio volume on most tracks seemed to be low. You might check to
see that
the volume is appropriate before you rip the CDs.
The DVD Audio jewel case is yet another size! It is larger than a CD
case, smaller than a DVD Video case, and is wider than both. What are
these guys thinking?
No doubt this excercise took more time than it was worth to go out and
buy the CD. But what fun is that?
you at cs.ucsc.edu